1. Field of the Invention
This invention relates broadly to spa tubs. More particularly, this invention relates to covers for spa tubs and systems for lifting and replacing a spa tub cover relative to a portable spa tub.
2. State of the Art
Spa tubs are frequently used for relaxation, physical therapy, personal enjoyment, and for social occasions. One of the appealing attributes of a spa tubs is that the tub includes jets that direct warm pressurized water toward an interior portion of the tub. Water that exits the jets and contacts the user's skin can create a massaging effect that is pleasurable, and even rehabilitative.
Spa tubs come in two forms: permanent in-ground installations and ‘portable’ above-ground installations. Portable spa tubs include a frame that supports a molded tub shell, and a cabinet surrounding the frame. The tub shell has an upper boundary rim, a plurality of seating locations defined by seat bottoms and backs and reclining lounges, and a lower floor. At one or more of the seating locations hydrotherapy jets are installed and a suction fitting is provided near the floor. Between the spa shell and the cabinet a space is defined in which plumbing and manifolds are provided to connect the jets, as well as one or more water pumps that circulate the water and a heater that heats the water circulated by the water pumps.
Referring to prior art FIGS. 1-2, for purposes of energy efficiency and readiness of use, it is common to provide the spa 10 with an insulative cover 12 that limits heat loss from the water when the spa is not in use. Such a spa cover 12 includes first and second portions 14, 16 of equal size that together are sized to seat on and cover the upper rim 18 of the spa tub shell 20. Each of the first and second portions 14, 16 are constructed of insulative foam slabs provided within a water-resistant vinyl casing material. The second portion 16 is movable relative to the first portion 14 on a living hinge 22 that connects the first and second portions at their opposing inside upper corners 24, 26 so that the first portion 14 can be folded back over the second portion 16 (FIG. 2). The hinge 22 is constructed of the same vinyl material as the casing material. In order to prevent premature wear of the hinge 22 during folding, the hinge is sufficiently wide to prevent it from being subjected to excessive strain. This creates a gap 28 between the first and second portions when the cover is in the closed configuration. ‘Premium’ spa covers may include a spacer 30 to limit heat loss from the gap. However, such a spacer 30 does not entirely prevent heat loss at the gap. The spa cover 12 may also include a skirt 32 that further assists in preventing heat loss from around the perimeter of the spa tub. The skirt 32 also prevents heat damage to the tub shell 20, particularly at or near the rim 18, which can become heat-damaged if exposed to sunlight for long periods of time without protection.
To remove the spa cover 12, the second portion 16 is folded back onto the first portion 14. The first and second portions are then together lifted off the spa 10. Often a cover lifter 34 (FIG. 3) is provided for mechanical advantage to assist a user in lifting the cover and to temporarily hold the cover in a folded generally vertically orientation during spa use. The cover lifter seats on the cover and provides a bar which extends over the hinge and about which the second portion is folded back onto the first portion. The bar is then rotated to lift and support the cover at the hinge.
Once the spa cover 12 is lifted, it is appreciated that the upper surfaces 36, 38 of the first and second cover portions 14, 16, as designated in the flat (or closed) configuration of the cover, are now located in the middle and in contact, whereas the lower surfaces (underside water facing surfaces) 40, 42 are facing outwardly from each other. It is not uncommon for the lower surfaces 40, 42 to become discolored by fading or staining due to long-term placement over the spa tub water. As a result, when the folded cover 12 is raised for use of the spa (prior art FIG. 3), the unsightly discolored lower surface 40 of the first portion 14 faces the users in the tub 10.
In addition to heat conservation, spa covers are also important for safety reasons. Spa covers include child-locks, such as child-resistant strap locks 44, that retain the cover 12 over the spa tub 10 by engagement in latches 46 to prevent children from entering the tub when the cover is down. With the cover design shown in prior art FIG. 2, multiple locks 44 are required to hold down the cover 12; at least one lock is required for each of the first and second portions 14, 16, and more commonly two locks are provided to each such portion, particularly adjacent the corners (for a total of four locks), to prevent the respective cover portion from being lifted in a manner that would permit a child to enter under the corners of the cover and into the tub.